A number of vital signs monitoring devices are known that are capable of measuring multiple physiologic parameters of a patient wherein various sensor output signals are transmitted either wirelessly or by means of a wired connection to at least one remote site, such as a central monitoring station. U.S. Pat. No. 5,319,363 describes a wired version of such a device and network, while U.S. Pat. Nos. 6,544,173 and 6,544,174 each describe a multi-parametric vital signs monitoring device that is linked by means of a bi-directional wireless communications network with at least one central monitoring station, usually located at a nurse's station on a hospital floor or Intensive Care Unit (ICU). Such monitoring systems have dramatically improved the manner in which patients can be monitored during a hospital stay. However, there is a perceived need in the field to provide a patient monitoring device that is truly versatile, such that the device can be selectively used for bedside as well as ambulatory applications in order to more effectively cover the varied number of situations a monitored patient may encounter, but without a loss in device (e.g., monitoring) connection with that patient or in obtaining required physiologic data.
There are additional concerns that exist in the field of patient vital signs monitoring. For example, the nature of monitoring devices that continuously monitor SpO2 (blood oxygen saturation) levels of a patient can cause false or nuisance alarms, particularly those patients who are of lower acuity or are ambulatory. Traditional continuous monitors of this type are found in ICU, OR, ED, PACU and other specialty beds, for the most part. The majority of hospital beds, on the other hand, are found in medical-surgical and/or general care areas in which non-continuous, spot-checking monitoring devices are primarily used. It is believed that present hospital healthcare dynamics, such as the general shortage of nurses, has increased pressure for regulatory compliance, rising costs, and higher acuity in patient census. The latter, it is further believed, could cause a convergence of continuous monitoring and spot-checking to the un-monitored beds of the hospital. A very large challenge or barrier to this trend is that clinical staff members on medical surgical floors are generally ill-trained or adequately skilled in the use of continuous medical monitoring devices.
There is yet another general need in the field of patient vital signs monitoring to improve the level of alarm management with regard to existing physiologic monitoring devices. Most known devices of this type include at least one visual and/or audible alarm that is produced, typically both at the monitoring device (e.g., bedside) as well as at the central monitoring station. According to one currently known monitoring system, the preset upper and lower alarm limits for all physiologic parameters can be automatically changed simultaneously a single time by a user simultaneously by a specified percentage (e.g., 20 percent). While this form of management/updating is often suitable for certain parameters, such as heart rate, it is not practicable for other parameters (e.g., SpO2). Though some monitoring devices further permit manual adjustment of alarm limits, this adjustment can be a somewhat time consuming and tedious process. As a result, there is a general desire to improve alarm management over presently known patient monitoring devices.
Additionally, there are also a number of patient monitoring devices that can indicate when an electrode assembly, such as those used for ECG electrode assemblies, has already reached failure or has become detached from the patient, such as those described by U.S. Pat. No. 5,819,741 to Karlsson et al. It would be even more desirable, however, to provide a patient monitoring device that can in addition to the above features proactively detect the onset of failure in at least one leadwire/electrode such that the at least one electrode or leadwire could be retrofitted in advance of having the ECG electrode assembly fail during examination or during rounds.
It is a desirable function of any cardiac monitoring device to provide sufficient information so that a clinician can discern if an implanted cardiac pacemaker is operating properly. Basically, it is desirable to include in the ECG waveform a highly visible indication each time the pacemaker fires. As the technology for implanted pacemakers and implanted pacing electrodes has evolved, the magnitude and duration of the pulses that result at the body surface have reduced, making these pulses more difficult to detect. Furthermore, the observed pacer pulse amplitude is smaller in some ECG vectors than in others. Which ECG vectors have the strongest pacer pulse signals is dependent on body surface ECG electrode placement and the location of the implanted pacemaker electrodes, and therefore the detection issues vary from patient to patient. Making the pacer pulse detector in an ECG monitoring device be able to detect smaller amplitude, shorter duration spikes unfortunately causes the detector to trigger more often on the electrical noise spikes that often occur in the patient's vicinity. Faulty incandescent light dimmers, fluorescent lights, electronic power supplies, and other assemblies generate electromagnetic interference (EMI) and other sources of electronic noise may generate such noise spikes, these spikes occurring at a rate that is twice the frequency of the power line. If a pacer pulse detector is triggered this rapidly, it is extremely difficult for the monitoring device to calculate an accurate heart rate. The extent to which these noise spikes affect a pacer pulse detector is further affected by the contact impedance of the body surface ECG electrodes—higher impedance connections make it more likely that these noise spikes will trigger the pacer pulse detector. For each of the foregoing reasons it is therefore desirable to be able to select as an input to a monitor's pacer detector, an ECG vector that contains real pacer pulses whose amplitude is sufficiently above the detection threshold, and which also contains environmental noise spikes whose amplitudes are sufficiently below the detection threshold. To that end, it would be desirable to be able to identify localized areas or sources of electrical noise, in order to permit the clinician to move the patient and/or noise source and thereby avoid instances of premature alerts or other similar situations.
It is yet another general desire in the field of remote monitoring to provide a multiple physiologic parameter monitoring device that is more user-friendly than previous devices of this type; that is, a device that can be more easily and effectively used by staff of varying skill levels.
Still further, there is a general need to provide a more rugged and durable patient monitoring device, given that such devices are finding increased uses, for example, in military field applications, requiring devices of this type to be much more tolerant to shock and environmental loads than those found in classical hospital environments.